Magnetic speed-indicator.



No, 759,041. PATENTED MAY 3, 1904.

v S 'B. STORER. MAGNETIC SPEED INDICATOR.

APPLICATION TILED APR. 16. 1903.

IlNiTED STATES Patented May 3, 1904.

ATENT OFFICE.

MAGNETIC SPEED-INDICATOR.

SPECIFICATION forming part of Letters Patent No. 759,041, dated May 3, 1904.

Application filed April 16, 1903. Serial No. 152,884. (No model.)

To all whom, it warty concern.-

Be it known that I, SIMON B. SToRER, of Syracuse, in the county of Onondaga, in the State of New York, have invented new and useful Improvements in Magnetic Speed-Indicators, of which the following, taken in connection with the accompanying drawings, is a full, clear, and exact description.

This invention relates to certain improvements in magnetic speed-indicators of the class set forth in my Patent No. 680,988, dated August 20, 1901, in which a revoluble element and an oscillatory member are both movable in the field of a permanent magnet to be cut by the same lines of force, so that the drag produced by the revoluble part exerts a degree of pull upon the oscillatory member sufficient to move the latter element from its normal position of rest, the amount of movement being proportionate to the speed of rotation of the revoluble part, which speed is measured by suitable graduations on the oscillatory member. In this class of instruments the magnet is stationary and is formed with concentric annular poles, between which the revoluble parts are movable. One of these movable parts is formed of soft iron or steel and may be termed the inductor, while the other movable part is usually made of copper or other low-resistance material, and, although the instrument is operative with either of the movable parts rotary and the other oscillatory, for convenience of description in the present application I have shown the soft-iron or steel inductor as revoluble and the low-resistance member as oscillatory. In the device shown in the patent referred to the periphery of the inductor is broken for forming a series of substantially radial teeth or pole-pieces, which serve to concentrate or bunch the magnetic lines of force which act inductively upon the oscillatory member to drag the same from its normal position of rest as the inductor is rotated. This oscillating element is made to assume a normal position ofrest by means of a suitable biasing device, after which the instrument is calibrated and graduated in the usual manner; but I have discovered that a true calibration could be more easily and permanently effected if the cross-sectional form of the pole-pieces of the inductor were made variable or extensible circumferentially, so as to vary the inductive effect or drag of the field, which acts to move the oscillatory member from its normal position.

The primary object of my present invention is therefore to facilitate the calibration of the instrument by making the inductor in two parts, so that one may be adjusted cir- I Fig. 5 is a view similar to Fig. 4, the cross-sectional outline of the teeth being shown in dotted lines.

Similar reference characters indicate corresponding parts in all the views.

In the drawings I have shown a cylindrical permanent magnet having inner and outer concentric pole-pieces l and 2 and a substantially central opening? Journaled within this opening upon suitable ball-bearings 4 is a revoluble element5, of soft-iron or steel, and composed of a hub 6 and annular rings 7 and 8, both of which are mounted side by side upon the hub 6 in close contact with each other and are movable between the poles 1 and 2 of the permanent magnet, said rings being provided with peripheral projections or polepieces 9 and 10. One of theseinductor rings or sections, as 8, is movable circumferentially relatively to the other section, so that the teeth or pole-pieces 10 are adjustable circumferentially across the gaps or spaces between the teeth of the other section for varying the cross-sectional form of the pole-pieces of the inductor. of a train of gears 11 and a suitable spur, which is keyed to the spindle of one of the gears and is adapted to engage the revoluble part, the speed of which is to be determined. it is thus seen that the toothed inductor 5 is rotated in the lield of the permanent magnet between the poles 1 and 2 and produces a certain drag of the lield proportionate to its speed of rotation. A cylindrical low-resistance element 12 is mounted to oscillate in the lield of the magnet between the pole-pieces 1 and 2 and biased to a normal position of rest by suitable counteracting springs 13, portions of the oscillating member 12 being interposed between the outer pole 2 and periphcry of the inductor 5, so as to be cut by the of the oscillatory member between the inductor and outer pole of the magnet being provided with a series of laterally-elongated apertures 14, which form a series of bars 15. 1t is evident that the drag produced by rethe permanent magnet acts inductively upon ber 12 and exerts a degree of pull upon the lat- This inductor is rotated by means teeth or pole-pieces of the inductor may be extended to entirely cover the gaps of the other imluctor-section, so that the distribution of the lines of force is substantially uniform, and therefore the inductive effect or pull upon the oscillatory member is reduced to a minimum, while, on the other hand, by adjusting the movable inductorrim circumferentially, so as to gradually uncover the space between the teeth of the ri ng-sections, the current is grad ually increased, and therefore the inductive el t'ect upon the oscillatory member is also increased. lt becomes apparent now that it for any reason the initial calibration of the instrument proves inaccurate in its reading such inaccuracy may be compensated by shitting the position of the movable inductor-ring same hnes of force of the magnet as those passing through the Inductor, said portions Now I relatively to the other in the manner described to vary the inductive effect upon the oscillatory member. in order to accomplish this adjustment, 1 provide the hub 6 with an annular flange 16, through which is inserted one or more screws 17, which pass through a 1 slot 18 in the adjacent ring 10 into threaded volvmg the inductor 5 between the poles of apertures 19 in the ring 9, the screws serving to lock the inductor-rings lirmly to the hub the interposed portions of the oscillatory memtcr member to move it from its normal position 01' rest, the amount of movement being proby means of which the degree of pull exerted j thereon, and consequently the speed of revolu- 3 tion, is accurately measured.

it will now be seen that the tufts of magnetic lines of force assume substantially the same form as the crosssectional form of the ad acent sections of each tooth ot the inductor and that the induced current set up by the lines of force through each pole-piece or tooth of the inductor would travel the combined toothed sections, as indicated by and at the same time permitting the ring 10 to be adjusted circumferentially when desired.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is

1. In a magnetic speed-indicator, a two-part inductor, one of the parts being adjustable relatively to the other to facilitate calibration of the instrument.

2. In a magnetic speed-indicator, a two-part inductor, one of the parts being adjustable circumferentially relatively to the other to vary the distribution of the lines of Force of the magnet.

3. In a magnetic speed indicator, two

toothed inductorsecti(,)ns, one being adjusttransversely in a course substantially coincident with the outline of the cross-section of which it will be observed that the ind uccd cur rent in the member 12"tollows the course of least resistance, which is through the bars 15 able relatively to the other to vary the cross sectional form of the teeth.

1. In combination with a magnet, a two-part inductor, one of the parts being adjustable relatively to the other and a low-resistance part, one of the two latter elements being rotatable with reference to the other.

nearest to the front and rear edges of the teeth of the inductor, and these openings or upon the oscillatory member, and by adjust mg the movable inductor-ring relatively to In combination with a magnet, a sectional inductor rotatable in the lield of the magnet,

1 one of the sections being adjustable relatively bars being substantially parallel it is evident to the other to vary the form of the inductionteeth or poles, and an oscillatory member actuated by the drag of the lield.

6. In combination with a magnet, an ind uctor rotatable in the lield of the magnet and y provided with sectional teeth or poles, one oi outer pole of the magnet were continuous. This adds materially to the drag eiliciency the other the circumferential length of the I the sections of each tooth being adj ustablc circum'lerentially relatively to the other to vary the form of the tooth, and an apertured coni ductor actuated by the drag of the lield.

7. in combination with a magnet, two iron In witness whereof I have hereunto set my hand this 31st day of March, 1903.

SIMON B. STORER.

Witnesses:

H. E. GHAsE, MILDRED M. No'm. 

